Recapitulation of the principal stages concerning the descriptive and the functional anatomy of the extensor apparatus of the ulnar digits. They can be written in the following frame: The Gálien's theories of the exclusive role of the extensor digitorum muscles prevail during more as a millenium. The indispensable conjoined action of the interosseus muscles through the collateral tendon is demonstrated by Duchene in 1867. The role of antagonistic muscles is clearly showed by Bouvier in 1851 on the level of the metacarpo-phalangeal joints and by Valentin and Tubiana in 1962 on the level of the proximal interphalangeal joints. The role of the oblique retinacular ligament on the extension of the third phalanx is specified in 1956 by Landsmeer.